1. Field of the Invention
The present invention relates to a display device, and more particularly, to a configuration of mounting terminals and inspection terminals of a display device in which a driving circuit chip for driving pixels forming a display area is directly mounted onto an array substrate.
2. Description of the Related Art
In recent years, a display device has been used as information display means for an observer in various apparatuses. Currently, instead of a Braun tube which has been mainly used so far, a new thin-type display device has been introduced which uses liquid crystal, plasma, EL (Electro Luminescence), or FED (Field Emission Display). In particular, since a small-sized model or a large-sized model can be manufactured in a liquid crystal display device, the liquid crystal display device is currently used as a typical thin-type display device.
In this kind of thin-type display device, plural pixels are arranged in a matrix shape to thereby form a display area. Additionally, in a frame area on the outside of the display area, a substrate is provided with mounting terminals which are connected to a driving circuit at the ends of wirings used for driving the pixels.
Among middle-sized or small-sized display devices, in a model which further requires a decrease in thickness and a decrease in manufacture cost or a model which requires vibration resistance for a vehicle or the like, a COG (Chip On Glass) mounting operation is widely used in which a driving circuit chip (driver IC) used for driving pixels in the display area is directly mounted to the mounting terminals formed on the substrate. Protrusion-shaped bump electrodes are respectively provided on the input side and the output side of the driving circuit chip, and the mounting terminals are arranged in correspondence to the positions thereof.
In a small-sized model such as a cellular phone or a digital camera, a high definition has been advanced, and a wiring pitch of the pixels considerably becomes small, that is, 40 micron or less. When the pitch becomes narrow, a position deviation occurs between the mounting terminals of the substrate and the bump electrodes of the driving circuit chip, thereby causing a problem of a difficult electric connection. Thus, in order to ensure a yield of the COG-mounting operation, the output-side bump electrodes and the output-side mounting terminals of the driving circuit chip have a two-row or more zigzag arrangement instead of a one-row arrangement, thereby increasing the pitch between the output-side bump electrode and the mounting terminal in each row by two times or more (for example, see JP-A-2006-10898 (FIGS. 1, 5, 7, and 9) and JP-A-2006-72032 (FIG. 5)).
Generally, in a manufacture process of the display device, a display inspection is carried out before the COG-mounting operation of the driving circuit chip in many cases. For this reason, an inspection terminal is separately provided in some cases in addition to the mounting terminals for the COG-mounting operation (for example, see JP-A-2006-10898 and JP-A-2006-72032).
As the display inspection, there are known a simple display inspection in which a common inspection terminal is provided for each terminal of colors, red, green, and blue so as to display only a simple screen and a precise display inspection in which inspection terminals are individually provided in correspondence to all output-side mounting terminals of a driving circuit chip and an inspection needle (probe) contacts with all inspection terminals so as to perform an arbitrary display.
In the former simple display inspection, several number of inspection terminals may be provided, but a precise inspection cannot be carried out. In addition, in the case where a defective state occurs due to static electricity upon cutting each wiring and the common inspection terminal for each color so as to be separated after the display inspection or in the case where each wiring and the common inspection terminal are configured to be in an OFF state via a TFT (Thin Film Transistor) switch during a time other than the display inspection, a problem may arise in that a yield is reduced when a defective state occurs in the TFT switch.
In the latter precise display inspection, the inspection terminals are individually arranged in zigzag in the same direction as the terminal-row direction at a position on the wirings connected to the mounting terminals arranged in zigzag in the frame area or a position where the wiring is further extended from each mounting terminal. The inspection terminal is different depending on positioning precision of an inspection device or a type of an inspection needle, but in general, the inspection terminal larger than the mounting terminal for the COG-mounting operation is required in many cases.
In recent years, since a frame width of the display device becomes narrow in order to ensure a maximum display area while maintaining the same external dimension of the display device, an allowance of an area (width) other than the COG-mounting area becomes small. Additionally, in order to cope with the narrow frame width, a width of the driving circuit chip becomes narrow.
From the viewpoint of a decrease in cost of the driving circuit chip, in order to increase the number of driving circuit chips obtained from one sheet of Si-substrate, a width of the driving circuit chip becomes narrow.
In the display device where the driving circuit chip is COG-mounted, in the case where the inspection terminals are individually provided in correspondence to the output-side mounting terminals of the driving circuit chip, the inspection terminal is disposed between the display area and the driving circuit chip in the liquid crystal display device disclosed in JP-A-2006-10898 and JP-A-2006-72032. For this reason, it is necessary to ensure an additional area used to form the inspection terminal in the frame area.
In addition, in order to prevent corrosion of the terminals, a protective resin is applied to an area where the terminals are exposed, but when the area having the exposed terminals increases, a problem arises in that a usage amount of the protective resin increases.